Biology subjects

Jendelova, P.

Publications and source records attributed to Jendelova, P..

13 recordsLinked to original sources

bioRxiv2026

Intertwined Autophagy and Integrin Dynamics Shape Axon Growth and Regeneration

Autophagy is a central pathway for cellular homeostasis, mediating degradation and recycling of cytoplasmic components through lysosomal processing. Although autophagy has been implicated in axon growth and neuronal injury responses, its role in axon regeneration remains incompletely understood. In parallel, integrin trafficking and focal adhesion dynamics are critical determinants of axonal growth, and increasing evidence indicates that autophagy regulates focal adhesion turnover in non-neuronal cells; however, whether this mechanism operates in neurons remains unknown. Here, we investigated the dynamics of autophagy during axon growth and regeneration in adult sensory neurons and examined its relationship with integrin trafficking. Using live imaging, we analyzed autophagic vesicles and integrin-containing compartments in axons under basal conditions and following axotomy. We find that axonal injury induces marked short- and long-term alterations in distal axon and growth cone autophagic vesicle dynamics, integrin trafficking, and autophagy-associated integrin turnover. Importantly, these changes correlate with axonal growth and regenerative capacity. Furthermore, we identify a functional interplay between autophagy and integrins, suggesting bidirectional regulation in which autophagy contributes to adhesion receptor recycling, while integrins feedback to modulate autophagy. Finally, pharmacological modulation indicates that autophagy plays a critical role in both axonal growth and regeneration, and that rapamycin enhances regenerative responses, likely through modulation of autophagy-dependent integrin recycling rather than a general increase in autophagic activity. Together, these findings reveal a bidirectional feedback system between integrin-mediated extracellular cues and autophagy-dependent intracellular trafficking that jointly orchestrates axon growth and regeneration.

neuroscience↗

bioRxiv2026

Modular in vitro evaluation of Buparlisib-polymeric nanomedicines in 2D and 3D models of glioblastoma

IntroductionIn this study, we developed a modular in vitro platform that integrates advanced polymer-drug conjugation chemistry with stepwise cytotoxicity screening in both 2D (monolayer) and 3D (spheroids) glioblastoma (GBM) models. Buparlisib was selected as the model therapeutic due to its well-characterised mechanism of action, high blood-brain barrier permeability, and relevance to PI3K-targeted therapy. MethodsTwo mechanistically distinct conjugation strategies were explored using N-(2-hydroxypropyl)methacrylamide-based copolymers. The first strategy was based on a redox-sensitive disulphide linkage designed for intracellular glutathione-triggered release, whereas the second used an azide-bearing derivative compatible with strain-promoted azide-alkyne cycloaddition. Drug release was assessed by high-performance liquid chromatography. Biological activity was systematically evaluated in U87MG, U118MG, and T98G cells under 2D conditions using a resazurin-based metabolic activity assay. Subsequently, the more promising disulphide-based formulations were assessed in 3D spheroids by metabolic activity measurements and live-cell monitoring of spheroid growth dynamics. ResultsFree Buparlisib showed the strongest inhibitory effect, while its modification and polymer conjugation reduced the apparent activity. Nevertheless, the disulphide-based derivative and polymer conjugate retained concentration-dependent activity, whereas the azide-based polymer conjugate showed minimal effects. Moreover, treatment responses differed between cell lines and between 2D and 3D models. DiscussionOverall, linker chemistry, cell-line-specific behaviour, and model dimensionality strongly influenced the biological performance of the polymeric Buparlisib formulations. The redox-sensitive polymer conjugate therefore represents the more promising strategy for further development.

pharmacology and toxicology↗

bioRxiv2026

4-Methylumbelliferone Restores Age-Related Changes in Perineuronal Nets, Memory and Neuroinflammation

Aging leads to cognitive decline due to reduced neuronal plasticity and increased brain inflammation. Disruption of perineuronal nets (PNNs) is a recognized strategy to enhance neuroplasticity. Hyaluronan forms the backbone of PNNs, and 4-methylumbelliferone (4-MU), an inhibitor of hyaluronan synthesis, has been proposed to disrupt PNNs and enhance neuroplasticity in young rodents. In addition, 4-MU is also known as an immune response regulator, although its effects within the central nervous system (CNS) have been less characterized. In this study, we investigated the impact of long-term oral 4-MU administration in aged mice (20-22 months old), focusing on PNNs intensity, memory, and neuroinflammation. PNN intensity increased with age, and 4-MU treatment reduced it in 22-month-old mice to levels observed in 10-month-old animals; in the novel object recognition test, treated 22-month-old mice performed comparably to or better than 10-month-old controls. Moreover, markers of aging-associated neuroinflammation--including astrocytic and microglial activation as well as peripheral immune cell infiltration--were normalized to 10-month-old levels or further diminished following 4-MU treatment. Importantly, chronic 4-MU administration was well tolerated in aged mice, with no serious adverse effects observed. Together, these results suggest that 4-MU mitigates PNNs accumulation and neuroinflammaging while enhancing recognition memory, supporting its potential as a safe therapeutic approach for age-related cognitive decline.

neuroscience↗

bioRxiv2026

Chondroitin 4-sulphate depletion enhances synaptic plasticity and memory in aging

Perineuronal nets (PNNs), specialised extracellular matrix structures enriched in chondroitin sulphate proteoglycans (CSPGs), are key regulators of synaptic plasticity, learning, and memory. Aging is characterised by a shift in chondroitin sulphate composition toward increased chondroitin-4-sulfation (C4S) and reduced C6S, a pattern associated with declining cognitive flexibility. Here, we investigated how selective reduction of C4S affects PNN structure, PV-interneuron connectivity, and cognitive performance across the lifespan. Conditional deletion of the C4-sulfotransferase Chst11 markedly reduced C4S levels and diminished dendritic PNN complexity while preserving somatic PNN structure. This partial destabilisation of PNNs increased excitatory synaptic input onto PV interneurons in both young and aged mice, without major alterations in basal hippocampal transmission or long-term potentiation. Behaviourally, Chst11 knockout mice showed robust and persistent protection against age-related cognitive decline. Working memory performance remained stable across aging, short-term spatial memory was enhanced from early adulthood onward, and object recognition memory was significantly prolonged at all retention delays, even in old age. Sociability and social novelty preference were also preserved longer in aging knockouts compared with controls. These improvements occurred despite an overall preservation of PNN architecture, indicating that modifying sulphation rather than removing CSPGs is sufficient to enhance plasticity. Our findings demonstrate that reducing C4S through Chst11 deletion confers long-lasting enhancements in cognitive function and mitigates aging-related decline. Targeting CS-GAG sulphation patterns may therefore represent a promising strategy for maintaining cognitive resilience and restoring plasticity in aging or neurodegenerative conditions.

neuroscience↗

bioRxiv2026

Long-Term Expression and Safety of AAV1-Mediated PI3Kδ Overexpression in the Adult Rat Cortex

Mature CNS neurons are incapable of sufficiently regenerating their axons following spinal cord injury (SCI). This is largely due to developmental changes in epigenetic control leading to suppression of axon growth transcriptomic profile, leading to a shift towards synapse function support. Recently, manipulating the PI3K/Akt/mTOR pathway through PI3K{delta} overexpression in cortical neurons enhanced axonal regeneration of corticospinal tract axons, which was accompanied by functional recovery monitored for up to 16 weeks. However, PI3K is more widely known for its role as an oncogene, and since overexpression is achieved by the use of AAVs, valid safety concerns are raised as it is unknown what the long-term consequences of sustained PI3K{delta} expression in the brain are, which may be necessary to achieve complete re-establishment of the motor pathway. In this study, AAV1-hSYN-PIK3CD was injected into the motor cortex of rats, which survived for 1 year. Comparison with uninjected control animals reveal stable PI3K{delta} expression and sustained pathway activation through increased pS6. PI3K{delta}-treated animals show absence of tumour formation, neural soma hypertrophy, glial cell activation, or haematological or biochemical abnormalities. Thus, long-term neuronal PI3K{delta} expression appears to be well tolerated and may provide a safe and durable strategy to promote functional repair following SCI.

neuroscience↗

bioRxiv2025

Dibutyryl cyclic AMP downregulates tenascin-C in neurons and astrocytes and reduces AAV-mediated gene expression in DRG neurons

Functional recovery after spinal cord injury (SCI) is hindered by the limited ability of axons to regenerate in the adult mammalian central nervous system (CNS). Overcoming this barrier is critical for achieving effective recovery. Axonal regeneration depends on the activation of intracellular processes like transcription factor induction, protein and lipid trafficking, and cytoskeletal remodelling. Targeting these pathways offers a promising approach for promoting neuronal repair. This study examined the combined therapeutic effects of dibutyryl-cAMP (db-cAMP), which primes neurons for growth, and integrin 9 overexpression, which supports axonal extension. Using in vitro models with dorsal root ganglion (DRG) neurons and astrocytes, as well as an in vivo SCI model, we evaluated the potential of this approach. In vitro, the combination of db-cAMP and integrin 9 significantly enhanced neuronal growth. However, in vivo results were less consistent, with db-cAMP affecting AAV-mediated transcription and the expression of tenascin C (TnC) in neurons and astrocytes. These findings highlight the potential of modulating intracellular signalling and integrin activation but underscore the challenges posed by the complexity of the in vivo environment. Further studies are necessary to unravel these mechanisms and refine therapeutic strategies for effective SCI recovery. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=136 SRC="FIGDIR/small/653846v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@1473630org.highwire.dtl.DTLVardef@36a8beorg.highwire.dtl.DTLVardef@80593corg.highwire.dtl.DTLVardef@6285e3_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2024

Dizocilpine derivatives with neuroprotective effect lacking the psychomimetic side effects

We aimed to prepare novel dibenzosuberane derivatives that act on N-methyl-D-aspartate (NMDA) receptors with potential neuroprotective effects. Our approach involved modifying the tropane moiety of MK-801, a potent open-channel blocker known for its psychomimetic side effects, by introducing a seven-membered ring with substituted base moieties specifically to alleviate these undesirable effects. Our in silico analyses showed that these derivatives should have high gastrointestinal absorption and cross the blood-brain barrier (BBB). Our pharmacokinetic studies in rats supported this conclusion and confirmed the ability of leading compounds 3l and 6f to penetrate the BBB. Electrophysiological experiments showed that all compounds exhibited different inhibitory activity towards the two major NMDA receptor subtypes, GluN1/GluN2A and GluN1/GluN2B. Of the selected compounds intentionally differing in the inhibitory efficacy, 6f showed high relative inhibition ([~]90% for GluN1/GluN2A), while 3l showed moderate inhibition ([~]50%). An in vivo toxicity study determined that compounds 3l and 6f were safe at 10 mg/kg doses with no adverse effects. Behavioral studies demonstrated that these compounds did not induce hyperlocomotion or impair prepulse inhibition of startle response in rats. Neuroprotective assays using a model of NMDA-induced hippocampal neurodegeneration showed that compound 3l at a concentration of 30 M significantly reduced hippocampal damage in rats. These results suggest that these novel dibenzosuberane derivatives are promising candidates for developing NMDA receptor-targeted therapies with minimal psychotomimetic side effects.

neuroscience↗

bioRxiv2023

Hyperactive PI3Kinase delta enables long distance regeneration of the rat corticospinal tract

Maturation of central nervous system neurons leads to loss of their intrinsic regeneration potential. In particular after injury of the adult spinal cord there is minimal regeneration of corticospinal axons, which control gait and fine movement. Previous work has shown that knockdown of PTEN to increase PIP3 levels can promote regeneration in young animals, but the effect is much less in adults probably due to low PIP3 production. Here, we have transduced sensorimotor cortex neurons with a hyperactive form of PI3K, PI3K{delta}, which increases PIP3 in mature neurons. This enables cortical neurons to regenerate corticospinal axons and improve behavioural outcomes. We used a C4 dorsal column lesion model in adult rats and injected the right motor cortex at 4 sites concurrently with a mixture AAV1-PIK3CD and AAV1-eGFP or titre matched AAV1-eGFP only. We allowed rats to survive for 6, 9, 12 or 16 weeks. Immunostaining showed 70 - 80% co-expression in cortical neurons which remained stable at both 12 and 16 weeks. We counted GFP labelled axons in 20 m spinal cord sections. In PI3KCD-treated animals many axons were seen to have regenerated around the margins of lesions, collecting into a knot of axons with the typical appearance of regeneration at the caudal end. Tracing down the cord, and excluding axons and neurites that could have come from unlesioned ventral CST, we found axons extending up to 1 cm below lesions, numbers decreasing with distance from the lesion. After 16 weeks there were circa 200 axons at the caudal end of lesions with a regeneration index of 0.2, with half this number at 12 weeks. Behavioural testing for 16 weeks revealed functional improvements in skilled paw reaching, grip strength and ladder rung walking in rats treated with PIK3CD compared to GFP only controls. In addition to behavioural testing, functional recovery of PIK3CD treated rats was confirmed with electrophysiological recordings during which we stimulated the right pyramid. Cord dorsum potentials (CDPs) above and below lesion and EMG forepaw distal flexor muscles showed greatly increased connectivity compared with GFP only controls, lesion only controls and uninjured shams. We conclude that forcing upregulation of PI3K{delta} in cortical neurons leads to robust regeneration after spinal cord injury that results in functional restoration.

neuroscience↗

bioRxiv2023

Alpha 9 integrin expression enables reconstruction of the spinal cord sensory pathway.

Full recovery from spinal cord injury can only occur if the axon pathways connecting the brain and spinal cord regenerate and restore motor and sensory connections. Neither sensory nor motor axons can regenerate spontaneously in the spinal cord in mammals. This failure is partly due to the lack of suitable adhesion molecules on the sensory axons that allows them to interact with the environment of the damaged spinal cord. In this rat study, an integrin adhesion molecule along with its activator was expressed in sensory neurons using an adeno-associated viral (AAV) vector. Expression of these adhesion molecules allowed sensory axons to regenerate through the spinal cord injury and all the way back to the brainstem, restoring the sensory pathway. Treated animals regained touch sensation and sensory behaviours. The integrin ligands in the injured spinal cord are tenascin-C and osteopontin, but adult PNS and CNS neurons lack receptors to them. Sensory neurons were transduced with 9 integrin, which combines with endogenous {beta}1 as 9{beta}1 (which is a tenascin/osteopontin receptor) together with the integrin activator kindlin-1. Regeneration from sensory neurons transduced with 9integrin and kindlin-1 was examined after C4 and after T10 dorsal column lesions with C6,7 and L4.5 sensory ganglia injected with AAV1 vectors. In animals treated with 9 integrin and kindlin-1, sensory axons regenerated through tenascin-C-expressing connective tissue strands and bridges across the lesion and then re-entered the CNS tissue. Many axons regenerated rostrally to the level of the medulla. Regenerated axons were particularly visible at the border between white and grey matter in the dorsal cord. Stimulation of the median/sciatic nerve caused many neurons rostral to the injury to activate and express cFos. VGLUT1/2 staining indicated newly formed functional synapses above the lesion. Behavioural recovery was seen in heat, mechanical sensation and tape removal tests. Many axons regenerated from the thoracic lesions to the brainstem, a distance of 4-5 cm, equivalent to the length of 1 or 2 spinal segments in humans.

neuroscience↗

bioRxiv2023

Oral administration of 4-methylumbelliferone reduces glial scar and promotes anatomical plasticity

Following a spinal cord injury (SCI), chondroitin sulfate proteoglycans (CSPGs) are up-regulated at the glial scar inhibiting neuroregeneration. Under normal physiological condition, CSPGs interact with hyaluronan (HA) and other extracellular matrix on neuronal surface forming a macromolecular structure called perineuronal nets (PNNs) which regulate neuroplasticity. 4-methylumbelliferone (4-MU) has been used previously to down-regulate HA synthesis but not been tested in SCI. In this study, we have evaluated the effect of 4-MU, an inhibitor of HA, in a chronic contusion model of SCI in rats. At a dose of 1.2 g/kg/day of 4-MU, we observed not only the reduction of HA in the uninjured spinal cords after 60 days of 4-MU administration, but also a down-regulation of CS glycosaminoglycans (CS-GAGs). In order to assess the effect of 4-MU in chronic SCI, rats with T8 spinal contusion injury were fed with 4-MU or placebo for 8 weeks in combination with daily treadmill rehabilitation for 16 weeks to promote neuroplasticity. 4-MU treatment promoted significant sprouting of 5-hydroxytryptamine (5-HT) positive fibres into ventral horns and reduced the HA synthesis by astrocytes around the lesion site. While 4-MU reduced astrogliosis in chronic stage of SCI, the current dose was not sufficient to down-regulate the increased production of CS-GAGs or behavioural performance. Together, these data suggest that oral treatment with 4-MU is able to induce anatomical plasticity but further adjustment on the dosage will be required to benefit functional recovery after SCI.

neuroscience↗

bioRxiv2023

4-methylumbelliferone enhances neuroplasticity in the central nervous system: potential oral treatment for SCI

Perineuronal nets (PNNs) are specialised extracellular matrix (ECM) structures that act as key plasticity regulators to the central nervous system. Removal of PNNs using chondroitinase ABC injections restores plasticity, however, there are limitations to its application to due to its enzymatic nature. Here, we explore the use of a small molecule 4-methylumbelliferone (4-MU) as an alternative non-invasive strategy to reversibly remove PNNs and enhance plasticity. Oral administration of 4-MU for 10 days successfully and dynamically removed PNNs in vitro. While 4-MU, preferentially downregulated hyaluronan in the spinal cord, a down-regulation of chondroitin sulphate proteoglycans is also observed in the cortex. Long term administration for 8-weeks administration revealed a partial removal of PNNs, and that injury-induced mechanisms promoting cortical structural plasticity are linked to endogenous modulation of ECM molecules. 4-MU is a new tool to unravel the limits of normal and pathological PNN-mediated plasticity.

neuroscience↗

bioRxiv2021

Integrin-driven Axon Regeneration in the Spinal Cord Activates a Distinctive CNS Regeneration Program

The peripheral branch of sensory dorsal root ganglion (DRG) neurons regenerates readily after injury unlike their central branch in the spinal cord. However extensive regeneration and reconnection of sensory axons in the spinal cord can be driven by the expression of 9 integrin and its activator kindlin- 1(9k1), which enable axons to interact with tenascin-C. To elucidate the mechanisms and downstream pathways affected by activated integrin expression and central regeneration, we conducted transcriptomic analyses of DRG sensory neurons transduced with 9k1, and controls, with and without axotomy of the central branch. Expression of 9k1 without the central axotomy led to upregulation of a known PNS regeneration program, including many genes associated with peripheral nerve regeneration. Coupling 9k1 treatment with dorsal root axotomy led to extensive central axonal regeneration and caused expression of a distinctive CNS regeneration program, including genes associated with ubiquitination, autophagy, endoplasmic reticulum, trafficking, and signalling. Pharmacological inhibition of these processes blocked the regeneration of axons from DRGs and human iPS-derived sensory neurons, validating their causal contributions. This CNS regeneration- associated program showed little correlation with either embryonic development or PNS regeneration programs. Potential transcriptional drivers of this CNS program coupled to regeneration include Mef2a, Runx3, E2f4, Tfeb, Yy1. Signalling from integrins primes sensory neurons for regeneration, but their axon growth in the CNS is associated with a distinctive program that differs from that involved in PNS regeneration.

neuroscience↗

bioRxiv2021

Perineuronal nets affect memory and learning after synapse withdrawal

Perineuronal nets (PNNs) enwrap mature neurons, playing a role in the control of plasticity and synapse dynamics. PNNs have been shown to have effects on memory formation, retention and extinction in a variety of animal models. It has been proposed that the cavities in PNNs which contain synapses can act as a memory store, which remains stable after events that cause synaptic withdrawal such as anoxia or hibernation. We examine this idea by monitoring positional memory before and after synaptic withdrawal caused by acute hibernation-like state (HLS). Animals lacking hippocampal PNNs due to enzymatic digestion by chondroitinase ABC or knockout of the PNN component aggrecan were compared with wild type controls. HLS-induced synapse withdrawal caused a memory deficit, but not to the level of naive animals and not worsened by PNN attenuation. After HLS, animals lacking PNNs showed faster relearning. Absence of PNNs affected the restoration of inhibitory and excitatory synapses on PNN-bearing neurons. The results support a role for hippocampal PNNs in learning, but not in long-term memory storage.

neuroscience↗